The present invention relates to a liquid fuel combustion apparatus, and more particularly to a liquid fuel combustion apparatus in which liquid fuel is vaporized and burned in a combustion cylinder.
A conventional combustion apparatus of this type, called a pot-type burner has a liquid fuel reservoir at the bottom of a vertical combustion cylinder. The fuel is vaporized from the fuel reservoir, and the vaporized fuel ascends by natural convection, while air is supplied through perforations in the peripheral wall of the combustion cylinder. Thus, diffusion burning is achieved, with the region of diffusion combustion extending from the bottom toward the top of the combustion cylinder. In this conventional apparatus, combustion takes place in coincidence with mixing of the vaporized fuel and the air. Actual excess air ratio is less than 1 in the lower part of the combustion cylinder, and the flame is elongated upwards. The temperature of the combustion gas is increased gradually, and at the top part of the combustion cylinder, actual excess air ratio is more than 1 and stable, smoke free, blue flame combustion is accomplished.
With this conventional apparatus, heat input or combustion rate can be adjusted over a wide range with the condition of constant airflow rate. However, a disadvantage of the apparatus is that it is relatively high because the combustion cylinder is set vertically and the flame is vertically elongated. This is particularly inconvenient when the combustion apparatus is incorporated in a heating apparatus such as space heater, and more particularly the heating apparatus is combined with an airconditioner.
Another type of conventional combustion apparatus has a horizontal combustion cylinder with a fuel reservoir in the center of the combustion cylinder in the vicinity of an end enclosed by an end plate. This apparatus has reduced height. However, since the fuel reservoir is positioned in the center of the cylinder, vaporized fuel concentration is higher in the upper portion of the combustion cylinder and lower in the lower portion, with the result that symmetry of combustion with reference to the axis of the combustion cylinder is lost. Also, the fuel reservoir is situated in the center of the combustion cylinder where the heat radiation from the flame is intensive. Accordingly, the liquid fuel in the fuel reservoir is subject to thermal decomposition producing combustion deposit in the fuel reservoir, and an ignition heater which is disposed to project into the fuel reservoir must be made of highly heat resistant materials. Furthermore, the fuel reservoir has to be accurately mounted to prevent the liquid fuel from spilling. And, even if the fuel reservoir is accurately mounted, there is a potential danger of spill of the liquid fuel, for instance, when the apparatus is vibrated.